Unlike antibodies, the T cells recognize antigen only in association with products of the major histocompatibility complex (MHC). Such dual recognition is mediated by combination of the variable regions of both the .alpha. and .beta. chains that comprise the antigen recognizing T-cell receptor (TcR). Recently it became possible to endow T cells with a given specificity by DNA mediated transfer of cloned genes coding for the .alpha. and .beta. TcR chains (Dembic et al., Nature, 320, 232-238 (1986)). In general, the expression as a dimer of both .alpha. and .beta. chains of a given TcR has been required in order to display a defined specificity although it has been implicated that the V.beta. is responsible for the MHC specificity (Saito et al., Nature, 329, 256-259 (1987)).
Expression of a chimeric receptor composed of immunoglobulin-derived V regions and T cell receptor-derived C regions has been achieved by Kuwana et al, Bioch. Biophys. Res. Comm., 149, 960-968 (1987). Expression was achieved in helper T cells and the criterion for expression was an increase in cytosolic calcium concentration. An increase in cytosolic calcium concentration, however, does not establish that one will obtain the various functional activities characteristic of a cellular immune response by helper cells or other lymphocytes.